A balance of theoretical and experimental work is aimed at understanding the decreased stroke volume, decreased dp/dt, and increased border zone mechanical stress which accompanies a myocardial infarction of a given size. Theoretical work involves large amplitude, nonlinear shell models of the infarcted ventricle in systole and diastole solved on a computer. Experiments simulate an M.I. in an open-chest dog with a paced heart. In these experiments, a servo-controlled syringe pump adds a compliance to the ventricle which simulates the presence of a noncontracting region.